This invention relates to a cylinder-type linear synchronous motor, and more particularly to a cylinder-type linear synchronous motor wherein a movable element carries out linear motion.
Currently, a cylinder-type linear stepping motor or linear pulse motor is commercially available as a cylinder-type linear motor. The cylinder-type linear stepping motor commercially available includes a stator constituted of a plurality of stator cores formed on an inner peripheral surface thereof with a plurality of small teeth so as to be arranged in an axial direction of a direct-acting shaft and having exciting windings wound thereon and a movable element including a movable section fixed on the direct-acting shaft, provided therein with permanent magnets and formed on an outer peripheral surface thereof with a plurality of small teeth in a manner to be arranged in the axial direction of the direct-acting shaft. In the linear stepping motor thus constructed, the exciting windings on the stator cores are excited in turn, to thereby permit thrust to be generated between the small teeth of the stator and those of the movable element, leading to linear motion of the direct-acting shaft. Unfortunately, the linear stepping motor fails to provide thrust at an increased magnitude, although it exhibits increased position control performance.
In view of the foregoing, the assignee proposed a cylinder-type linear synchronous motor which provides thrust at an increased magnitude although it is somewhat deteriorated in position control performance, as disclosed in Japanese Patent Application No. 130051/1998.
More particularly, the cylinder-type linear synchronous motor proposed is constructed into a structure that a plurality of annular windings are fitted in a plurality of slots of a stator core corresponding thereto, respectively. However, the structure causes the stator core to be designed for every motor varied in length in an axial direction thereof. Also, it renders assembling of the stator troublesome. Further, it fails to reduce a width of an opening of each of the slots positioned opposite to a movable element, to thereby enhance performance of the motor.